The Evolution of the Whale

The evolution of the whale has long been shrouded in mystery. Fossil remains have demonstrated features that suggest that the large mammals that we know as sea-dwellers actually once lived on land. This idea is not so far-fetched considering that whales possess large, developed brains, breath oxygen, are warm-blooded and give birth to live young, all of which are characteristics shared with most land mammals.

Experts believe that ancient "whales" had legs and were well suited for life on land. When these ancient mammals made their way back to the sea they shed their legs and their bodies adapted to an aquatic lifestyle. Interestingly, this is the reverse of what is thought to have happened millions of years ago, when the very first mammals are believed to have crawled from the depths of the sea to become land dwellers.

Not all of the details of whale evolution are clear and remain the subject of study. However, the transformation from land dwellers to sea dwellers is considered a certainty, as a great number of fossils have been uncovered in the past few decades, which demonstrate this amazing transition.

One of the most important discoveries concerning whale evolution was made in Pakistan in 1978 by paleontologist Phil Gingerich. These fossil remains resembeled wolf-sized carnivores (creodonts) that roamed the earth between 60 and 37 million years ago. However, the skull of these land-dwellers also had traits that were similar to those of the oldest known whale species (archaeocetes). These new fossil findings, named Pakicetus, demonstrated the transition between land dwelling mammals and fully aquatic animals. The most notable evidence of this came from an examination of the ear region of the creodonts, which showed adaptations not found in other land-dwelling animals of the time. This suggests an evolutionary tie to modern-day whales, whose ear regions are highly-modified for underwater hearing.